Phonograph recording arm clamp



Aug. 9, 1949. L. THOMPSON I PHONOGRAPH RECORDING ARM CLAMP Filed Sept. 8, 1945 2 Sheets-Sheet 1 IIIIV lll INVENTOR.

Patented Aug. 9, 1949 rH'oNoGnAPn RECORDING ARM CLAMP Lincoln Thompson, Cheshire, Conn., assignor to The Soundscriber Corporation, New Haven, Conn., a corporation of Connecticut Application September 8, 1945, Serial No. 615,223

6 Claims. (Cl. 27413) This invention relates to the art of sound recording and reproducing, and more particularly to an apparatus of the above nature in which a cam-actuated lifting rod raises the recording head during listen periods, and in which provision is made of a frictioneslipping clamping plate which will permit the manual swinging of the pivoted recording arm, even while it is clamped in listen position,

One obj t of the present inve tion is to p ovide an apparatus of the above nature in which the recording arm may be swung in either direction across the record without shifting the clam ing knob back to talk position.

A further object is to provide an apparatus of the above nature which, will be relatively simple in construct-ion, inexpensive to manuiacture, easy to install and manipulate, compact, ornamental in appearance, and very emclent and durable in use.

With these and other objects in view, there has been illustrated on the accompanying drawing one form in which the invention may conveniently be embodied in practice.

In the drawings,

Fig. 1 represents a top plan view of a portion of a, disk recording-reproducing dictating machine, showing the pivoted recording arm in operating position above the record on the turntable.

Fig. 2 is a sectional view of the same, taken along the broken line 22 of Fig. 1, and show.- ing the recording stylus in operating position res-ting upon the record.

Fig. 2A is a face view of the recording head lifting cam.

Fig. 3 is a detail sectional view of the same, taken along the line 3-3 of Fig. 2 as it appears when the recording head is raised above the record.

Fig. 4 is a fragmentary sectional view, taken along the line 4--4 of Fig. 3 of the resilient clamping plate and a portion of the recording arm.

The present invention relates more particularly to a dictating machine which is designed to operate on a thin hard disk record having closely spaced grooves and rotated at slow speed, such as was described in Patent No. Reissue 22,183, entitled Apparatus for recording sound on thin disks," original Patent No. 2,200,866, dated May 14,. 1940. In such an apparatus no material is removed from the record, the recording being done solely by indenting and embossing a groove on the surface thereof.

The present invention 5 an p 'e ent W 2 the dictating machine disclosed in my prior patents, No. 2,133,596, dated October 18, 1938, entitled Feed mechanism for disk recording machines, and No. 2,250,242,, dated July 22, 1941, entitled Disk dictating machine.

Referring now to the drawings in which the like reference numerals denote corresponding parts throughout the several views, the numeral ID indicates arecording head arm which is pivotally mounted to swing in a horizontal plane and which is frictionally driven from a feed shaft II. The arm Ill on its rear end has a depending power head I2, below which is a Weak friction-slipping fiber washer l2a located in contact with a collar I3 secured to the shaft I as by a set screw Id.

The feed shaft II is driven from an electric motor (not shown) by a horizontal stud shaft l5 through a gearing mechanisminc'luding a worm i6 and a Worm gear l1--the driving mechanism being similar to that'described in the above-mentioned patent, No. 2,250,242,

The recording arm ID is adapted to be driven at constant speed across the record R from the continuously rotating feed shaft I I by the frictional engagement of the collar [3 upon the fiber washer I2a which is held in abutment with the power head I 2 of the alm H] by a conical spring l8 and a headed screw l9 engaging a washer 20. By means of this construction, the recording arm It) may be fed across the record it without backlash.

The turntable T is preferably mounted at the forward portion of a chassis plate C, and the recording arm I 0 is preferably pivotally mounted on the right hand side of said chassis, as viewed in Fig. 1. I

It will be understood that while in the recording position, by means of the slip-.-friction mounting of the recording arm ID with respect to the drive shaft II, the recording head RH may be lifted and swung freely manually to any desired position with respect to the disk record R located on the turntable T.

When the operator is through recording, the recording head RH will be raised and clamped above the record by turning 9; selector knob 26a at the front of the cabinet (3 in a counterclock Wise direction, from the tails to the listen position, as viewed in Fig. 1. This action will cause a cam plate 20b, which is mounted upon a horizontal shaft 200, to move a cam roller 2| upwardly.

The cam plate 201: has a hub- 20d secured to the shaft 200 by a set screw 206. The cam roller 2! is rigidly mounted on a pin 22 having its ends mounted in a pair of bearings 23, 24 in a vertical follower yoke 25 secured by means of a pin 26 to the lower end of a lifting rod 21.

Secured to the rear of the recording head RH, as by a pair of screws 21a, is a U-shaped headlifting bracket 28 having a short wide front leg 29 and a longer narrow rear leg 30 located parallel thereto, as clearly shown in Figs. 1 and 2.

On the top of'the lifting rod 21 provision is made of an arm-clamping shoe 360. (preferably rectangular in shape) which is held in adjusted position by means of a lock nut 3| located therebeneath, said shoe 30a and nut 3| both being screwed upon a threaded upper end 3|a of the lifting rod 21.

Surrounding said lifting rod 21 is a loose circular washer 32 which is located in spaced position below the lock nut 3| so as to permit a limited vertical movement of the rear of the head-lifting bracket 28. The washer 32 is adapted to rest upon a thin resilient sectorshaped arm-clamping plate 33 having a closed curved slot 34 which freely embracesthe lifting rod 21.

The resilient clamping plate 33 is secured to the recording feed arm l -by means of a transverse rectangular spacing block 35, attached in position by means of screws 36, 36. Below the clamping plate 33 and surrounding the lifting rod 21 is an elongated threaded sleeve 31 upon the top of which is a collar 3% having a top flange 38 which is located adjacent the upper surface of the recording feed arm Ill.

The threaded sleeve 31 has a flange 38a. adjacent its lower end which serves as an upper abutment for a helical coiled spring 39, the lower end of which engages the bearings 23, 24. The flange 38a is adapted to engage the under surface of the chassis plate C, as clearly shown in Fig. 2. A nut 46 screwed on the sleeve 31 tightly engages the upper surface of the chassis plate C for holding the sleeve 31 rigidly in position. I

In order to mount the recording head RH pivotally upon the front of the horizontally swinging recording feed arm l6, provision is made of a rectangular spring hinge plate 4| secured as by screws 42, 42,'to a rearwardly-extending lug as on the bottom of said recording head RH. The rear of the hinge-plate 4| is attached as by screws 44, 44 to a depending lug 45-on the forward portion of the recording feed arm ID.

The recording feed arm; I8 is provided with a curved slot 46 open on its outer side and similar in shape to and aligned with the slot 34 in the clamping plate 33 previously described.

Operation When the operator has finished'dictating and wishes to play back the material already dictated, he will turn the control knob 28a from the right hand talk position tothe left hand listen position as shown in Fig. 1, causing the high portion of the cam 20b to swing downwardly, clear of its follower yoke roller 2| so that the helical spring 39 will force the rectangular clamping shoe 36a down against the rear leg 30 of the bracket 28, which will cause the head RH to swing upwardly in a clockwise direction, about its fulcrum on the spring hinge 4|, thereby lifting the recording stylus S from the record R.

At the same time, the bracket 28 will move downwardly against the loose washer 32 and cause the resilient clamping plate 33 to engage the collar 39b which rests onthe top of the upper sleeve 31. This will introduce a greater friction on the arm l6 than the fiber washer |2a exerts against the power head I2, and hence the recording arm l0 will remain stationary, and will not be driven by said power head. If, however, the operator desires to swing the recording head RH and the arm ID in either direction to reposition it for further dictation before lowering it to the record, it will only be necessary for him to grasp a handle 41 on the front of the head RH and move it in the desired direction, thus overcoming the friction between the resilient plate 33 and the flange 38. This repositioning may be performed without touching the control knob 2f|athus eliminating an operation which was required with the previous form of apparatus, described in Patent No. 2,250,242.

After the desired portion of the recorded material has been played back by the playback mechanism, not shown, the machine may readily be arranged for further dictation by turning the control knob Zllafrom the "listen to the talk position, as shown in Fig. 2. This causes the embossing stylus S to be lowered gently into contact with the record, and simultaneously shifts the circuit connections (not shown) from playback to recording.

In order to provide for the proper amount of lift of the recording head RH from the record, a sufficient clearance should be left between the lifting bracket 28 and the clamping shoe 30a when the control knob 20a is in the talk position.

It will be understood that the strength of the spring 39 and the coefiicient of friction between the opposite surfaces of the clamping plate 33 and the loose washer 32 on the one hand, and the flange 38 of the collar 39?) on the other hand, will be sufficiently large as to afford ample friction to prevent the elevated recording head from moving until desired.

One advantage of the present invention is that with the improved clamping device herein disclosed, a smooth friction surface may be applied to the thin resilient clamping plate 33 to provide sufliclent friction to hold the elevated recording arm ID from feeding during playback, and yet permitting said arm to be manually moved in any direction without harm to the friction surfaces. 7

A further advantage is that the resiliency of the thin clamping plate 33 will permit a certain amount of yielding, and will thus compensate for any irregularities which may exist in the mounting of the recording head, due to variations in mass production. I

While there has been disclosed in this specification one form in which the invention may be embodied, it is to be understood that this form was shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but maybe modified and embodied in various other forms without departing from its spirit. In short. the invention includes all the modifications and embodiments coming within the scopeof the following claims.

Having thus fully described the invention, what is claimed asnew, and for which it is desired to secure Letters Patent, is:

1. In a dictating machine of the phonographic type, a vertical feed shaft, a horizontally-movable arm carrying a vertically-movable recording head at its free end, slip-friction means for pivotally connecting said arm to said feed shaft for normally driving said arm at constant speed across a disk record, means to clamp said arm with sufiicient friction to overcome the driving force of said feed shaft, comprising a thin horizontal resilient clamping plate connected to said arm at an intermediate point thereof, a vertical rod passing through said arm, a horizontal clamping shoe at the upper end of said rod, said recording head having a rearwardlyextending bracket located below said shoe and adapted to be depressed thereby, a sleeve surrounding said rod and having an abutment flange at the upper end thereof, said flange being located below said clamping plate and engageable thereby when the latter is engaged by said bracket, for holding said arm against swinging movement, and means to lower said rod to simultaneously lift said recording head out of recording position and hold said recording arm.

2. In a dictating machine of the phonographic type, a horizontally-movable recording arm carrying a vertically-movable recording head at its free end, a vertical feed shaft connected to the rear end of said arm by slip-friction means for normally driving said arm at constant speed across a disk record, a resilient clamping plate located above said arm and connected at one end thereto, a rigid abutment located beneath said plate and normally out of contact therewith, and means to simultaneously raise said recording head from said record and force said clamping plate downwardly against said abutment to hold said arm and said head in rigid position and overcome the driving force of said feed shaft.

3. The invention as defined in claim 2, in which said clamping plate is secured in raised position above said arm by a spacer block which is attached to said arm.

4. In a dictating machine of the phonographic type, a pivotally-mounted horizontally-movable recording arm, slip-friction means for driving said arm at constant speed across a disk record, a resilient clamping plate located above said arm and connected thereto, a rigid abutment below said plate and normally spaced therefrom, a vertical lifting rod passing through said arm, said plate and said abutment, means on the top of said rod to simultaneously raise said recording head from said record and force said clamping plate against said abutment to hold said arm in rigid position, said clamping plate having a curved closed slot embracing said lifting rod, and said recording arm having a curved open slot also embracing said lifting rod located in alignment with said closed slot.

5. In a dictating machine of the phonographic type, a pivotally-mounted horizontally-movable recording arm, slip-friction driving means for causing said arm to move at constant speed across a disk record, a resilient horizontal clamping plate located above said arm and rigidly connected thereto at one end, an abutment normally spaced below said plate, a vertical lifting rod passing through said arm and said plate, means on the top of said rod for simultaneously raising said recording head from the record and forcing said clamping plate down against said ,abutment to hold said arm against swinging movement, and spring means to normally hold said rod in lowered position.

6. In a dictating machine of the phonographic type, a horizontally movable recording arm having a recording head at its free end, slip-friction means for driving said arm at constant speed across a disk record, a vertically resilient clamping plate on said arm, a fixed abutment below said plate, and manually operated means to depress said plate against said abutment and produce a slip friction engagement therewith for holdin said arm with a force sufiicient to overcome the force of said slip-friction driving means, and insufficient to prevent manual movement of said arm with relation to said driving means.

LINCOLN THOMPSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,133,596 Thompson Oct. 18, 1938 2,250,242 Thompson July 22, 1941 2,295,712 Brown Sept. 15, 1942 2,357,033 Thompson Aug. 29, 1944 

